1. Field of the Invention
The present invention relates to a thermal transfer printer that ink on an ink ribbon is transferred to a sheet of paper for recording through selective heating of heat generating elements of a thermal head, and more particularly to a thermal transfer printer capable of selectively performing recording with thermal fusion transfer and recording with thermal sublimation transfer at operator's option.
2. Description of the Related Art
A thermal transfer printer generally records images, such as desired characters, on a sheet of paper as follows. A sheet of paper is supported in front of a platen and a thermal head made up of a plurality of heat generating elements is mounted on a carriage. An ink ribbon as one example of ink films each comprising a base member and desired type of ink coated over the base member is held, along with the sheet of paper, between the thermal head and the platen. While the thermal head is reciprocated along the platen with the carriage, the ink ribbon is reeled out and the heat generating elements of the thermal head are selectively energized to generate heat in accordance with information to be recorded. Such a thermal transfer printer is widely employed as output units of computers, word processors and so on because of high recording quality, low noise, low cost, and easiness in maintenance.
In many of conventional thermal transfer printers, images are recorded on a sheet of paper by using an ink ribbon (heat-fusible ink ribbon) formed of a base member, such as a plastic film, coated with heat-fusible ink. However, there is also known another type of thermal transfer printer that images are recorded on a sheet of paper by using an ink ribbon (heat-sublimated ink ribbon) formed of a base member coated with heat-sublimated ink.
Of those conventional thermal transfer printers, ones recording images on a sheet of paper with heat-fusible ink ribbons (hereinafter referred to as heat-fusion thermal transfer printers) are superior in practical convenience because they can make recording on various types of paper such as plain paper, thick paper and post cards.
On the other hand, thermal transfer printers recording images on a sheet of paper with heat-sublimated ink ribbons (hereinafter referred to as heat-sublimation thermal transfer printers) employ specific paper having been subjected to surface treatment and are able to produce recording images with high quality comparable to silver salt film photography.
Heretofore, heat-fusion thermal transfer printers and heat-sublimation thermal transfer printers have been separately put into practice as different types of thermal transfer printers because of different characteristics of ink used.
But the conventional thermal transfer printers stated above have had problems below due to separation into heat-fusion thermal transfer printers and heat-sublimation thermal transfer printers in commercialization. When it is required to make both types of recording, i.e., general recording on usual paper and high-quality recording on specific paper comparable to silver salt film photography, two units of different thermal transfer printers, i.e., a heat-fusion thermal transfer printer and a heat-sublimation thermal transfer printer, have to be prepared. This needs a large space for installation and increases economic burden.
Accordingly, there has been a demand for a thermal transfer printer which can selectively realize recording using a heat-fusible ink ribbon and recording using a heat-sublimated ink ribbon by one unit.
The applicant has previously proposed a serial thermal transfer printer capable of optionally using a heat-fusible ink ribbon and a heat-sublimated ink ribbon. However, because electric energy to be applied to a thermal head for recording differs largely between the thermal fusion recording and the thermal sublimation recording, the control process requires to be changed depending on a recording mode used. This has resulted in a complicated mechanism to realize recording with good quality in any of the recording modes without damaging ink ribbons.